A fan that will be mounted in a ventilation hole. If the temperature rises over a limit the fan will start and run until the temperature is under a certain point. Although the fan is extremely quiet a LDR is used to keep the fan quiet at night. Status: Has been running without problems for two years. The fan is so quit and nights can be hot so the LDR is not used. Schematic: Code (for mikroC): #define fan GPIO.GP5 int potTemp, potTime, light, temp; long int delayTime; void main() { //Settings OPTION_REG = 0b11010000; //GPIO pullup and TMR0 setup //GPIOs TRISIO = 0b00010111; //A/D. Fosc/2, AN<3:0> activated. ANSEL = 0b00001111; //ADCON0. 0 (ADFM), 0 (Vref=VDD),00 (dont care),10 (channel select, chan 02),0 (Go/Done), 1 (AD is on) ADCON0 = 0b00001101; fan = 1; do{ // Loop potTime = Adc_Read(0); //Left pot AN0, pin7 potTemp = Adc_Read(1); //Right pot AN1, pin6 //light = Adc_Read(2); //LDR temp = Adc_Read(3); //TC1047 /* The temp potentiometer can have values from 0-5V, ie 0-1023 (10-bit A/D). */ temp = temp - 140; temp = temp * 50; if (temp > potTemp) { fan = 1; } if (temp < potTemp) { fan = 0; } //Wait a second delayTime = potTime * 3000; Vdelay_ms (delayTime); } while(1); }